Case Area Targeted Interventions (CATIs) in Cholera Outbreak Response

Case management - Epidemiology surveillance - Water, Sanitation and Hygiene (WASH) completed

Project timeline: 31/03/2021 - 31/05/2022

Lead Researcher

Dr. Paul Spiegel

Organisation / Institution

Johns Hopkins University School of Public Health (JHSPH), Center for Humanitarian Health


USAID - United States Agency for International Development

Project summary


Evaluate the effectiveness of the Case Area Targeted Intervention (CATI) approach in reducing the incidence of new cases during cholera outbreaks.  And in so doing, to determine factors that support optimal delivery and interventions for CATIs towards cholera reduction in humanitarian settings and fragile states.


The primary aim is to characterize the relationship between CATI activation time (time between case presentation at a cholera treatment facility and the start of the CATI intervention) and cholera incidence in the area covered by CATI interventions. Secondary aims include:

  • Document procedures of implementing CATIs and develop recommendations to maximize their impact in future cholera outbreaks.
  • Describe the integration of water, sanitation, and hygiene (WASH) and health activities delivered via CATI.
  • Characterize the relationship between CATI completeness (in terms of coverage within the specified geographic area and activities implemented within households) and incidence of new cholera cases.
  • Estimate CATI effectiveness using secondary parameters (e.g. reported diarrheal incidence, free chlorine residual (FCR) in the drinking water sample, and knowledge and practices to prevent cholera transmission).
  • Document coordination mechanisms between Ministries, United Nations (UN) agencies, Clusters, and non-governmental organizations (NGOs) and develop recommendations for coordination in future responses.

Study Design

The proposed research will be conducted in future cholera outbreaks that take place in recognized humanitarian contexts in at least two different countries; locations will be selected based on where cholera outbreaks occur and the presence of a CATI implementing partner.  Organizations that frequently implement CATI interventions during cholera response that have agreed to partner with JHSPH include Action Against Hunger, Solidarités International, and Medair. Countries with humanitarian emergencies that are at high risk of cholera outbreaks include Democratic Republic of the Congo, Nigeria, Ethiopia, Mozambique and Yemen, though it is possible that other humanitarian contexts may serve as a research location if a cholera outbreak occurs and one of the aforementioned implementing partners responds with a CATI intervention.

The JHSPH IRB approval has classified this study as Non-Human Subjects Research.   Government or IRB approval will be attained prior to conducting the research.

The research team will be present at the site as soon as possible after the first cholera case has been documented and begin data collection as soon as feasible. If travel to the study location is not feasible for security reasons, the JHSPH research team will conduct the study remotely through the partner organization that is providing on-the-ground CATI response to the cholera outbreak.

Because the aim of the research is to evaluate CATIs as delivered by NGOs in response to a cholera outbreak, a randomized design is not possible. Thus, we will rely on comparison groups that will occur naturally, according to the outbreak size and capacity of the response organization. This will necessitate a flexible sampling approach.

We anticipate the primary comparison will be rapid vs. delayed CATI implementation (e.g. end stage of outbreak); however, it is also possible that areas with no CATI implementation could be used as a comparison group [in outbreaks where there is insufficient capacity to respond to all cases].  Additional points of comparison may include the delay between case presentation and CATI implementation:  e.g. CATI implemented within 24h, in 2 days, in 3 days, in 4 days, etc.

The proposed research is an observational study of cholera interventions implemented by NGOs in response to cholera outbreaks (i.e. no intervention is proposed).  The study will include the following components:

  • Observation of CATI delivery
  • Key informant interviews: 1) NGO staff members delivering the CATI intervention to characterize perceived strengths and weakness of the intervention, household selection, logistical processes and implementation challenges; 2) Humanitarian response managers from the partner NGO, UN agencies, national governments and other organizations engaged in the cholera response to ascertain perceptions of the response, coordination and CATI delivery and implementation
  • Cholera treatment facility line lists: Information from cholera line lists is used to plan CATI interventions, where each individual on the line list (i.e. a cholera case) receives a household visit from a CATI team. The JHSPH study team will request line lists from health facilities [which may be augmented by the study team] to evaluate coverage of CATI interventions.
  • Follow up survey: The household follow up survey will be conducted approximately 14 days after the presentation of the suspected cholera case at a cholera treatment facility. The exact sampling approach will depend on the density of housing in the community and the CATI implementation strategy. Household surveys will enquire about receipt of the CATI intervention, household composition, incidence of diarrhea and diarrhea care seeking among household members in the period since CATI implementation (or case presentation if there was no CATI), knowledge and practices of hygiene behaviors and observation of free chlorine level (FCR) in stored drinking water.

Lay summary

Cholera continues to pose a major global public health threat and is a marker of inequality and poverty as it reflects the lack of access to basic water and sanitation infrastructures. The risk of the spread of cholera is particularly high in humanitarian settings and fragile contexts.

Cholera transmission risk is higher for cholera case household members and nearby households. Mass interventions to contain cholera outbreaks are not resource efficient.  Preventive interventions targeting cholera case-households and neighbors have been found effective in past outbreaks. These interventions are often referred to as case area targeted interventions (CATIs). CATIs predominantly include water, sanitation, and hygiene (WASH) activities but can also include epidemiological surveillance, and health (clinical) services, primarily oral vaccination and antibiotic chemoprophylaxis.

There are limited studies on the best practices and effectiveness of CATIs in humanitarian settings.   This study aims to identify those factors that support optimal delivery and interventions of these CATIs for cholera reduction in humanitarian settings and fragile states.  The study design centers around observing the CATI activities of partner organizations as they respond to a cholera outbreaks in known humanitarian or fragile settings.

Potential for public health impact or global health decision-making

There is limited evidence studying the mechanisms, composition, interventions, timing, effectiveness of CATIs in humanitarian settings. This proposed research for CATI in humanitarian settings will focus on variations in CATI implementation and timing, monitoring and evaluation, and coordination and integration with the aim of expanding available evidence that can be used to inform the development of operational guidance for CATI interventions in cholera response.


Chiara Altare, PhD, Assistant Scientist, JHBSPH Department of International Health and Center for Humanitarian Health
Andrew Azman, PhD, Associate Scientist, JHBSPH Department of International Health and Center for Humanitarian Health
Shannon Doocy, PhD, Associate Professor, JHBSPH Department of International Health and Center for Humanitarian Health
Gurpreet Kaur, MD, MPH, Research Associate, JHBSPH Department of International Health and Center for Humanitarian Health
Mustafa Sikder, PhD, Research Scientist, Institute for Health Metrics and Evaluation

Key Collaborators

Action Against Hunger
Action Contre Le Faim
Health Cluster
Solidarités International
WASH Cluster

Resources (1)


Retrospective Case Studies on Case Area Targeted Interventions for Cholera Epidemics